9 Troubleshooting
9 - 8
NX-series Digital I/O Unit User’s Manual (W521)
80200000 hex NX Unit I/O
Communica-
tions Error
An I/O communica-
tions error occurred
in an NX Unit.
For the NX bus of CPU Units
• An error that prevents normal
NX bus communications
occurred in a CPU Unit.
• An NX Unit is not mounted
properly.
• The power cable for the Unit
power supply is disconnected,
or the wiring from the Unit
power supply to the NX Units is
incorrect.
• The power cable for the Unit
power supply is broken.
• The voltage of the Unit power
supply is outside the specified
range, or the capacity of the
Unit power supply is insuffi-
cient.
• There is a hardware error in an
NX Unit.
For Communications Coupler
Units
• An error that prevents normal
NX bus communications
occurred in a Communications
Coupler Unit.
• The NX Unit is not mounted
properly.
• The power cable for the Unit
power supply is disconnected.
Or, the wiring from the Unit
power supply to the NX Units is
incorrect.
• The power cable for the Unit
power supply is broken.
• The voltage of the Unit power
supply is outside the specified
range. Or, the capacity of the
Unit power supply is insuffi-
cient.
• There is a hardware error in the
NX Unit.
√ P. 9 - 1 3
80210000 hex NX Unit Out-
put Synchro-
nization Error
An output synchro-
nization error
occurred in the NX
Unit.
For the NX bus of CPU Units
• I/O refreshing on the NX bus is
not performed normally due to
an error in the CPU Unit.
For Communications Coupler
Units
• The communications cable con-
nected to the Communications
Coupler Unit is broken or the
connection is faulty.
• The communications cable is
affected by noise.
√ P. 9 - 1 5
Event code Event name Meaning Assumed cause
Level
Reference
Maj Prt Min Obs Info
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